In the related art, a mechanism is known in which a double pinion type planetary gear is used as a speed reduction mechanism which can coaxially arrange an output shaft and an input shaft (for example, refer to Patent Document 1). As illustrated in FIG. 12, the double pinion type planetary speed reduction mechanism is configured so that a first pinion gear 301 and a second pinion gear 302 which are connected to each other are rotatably attached to a carrier 304 connected to an output shaft 303, the first pinion gear 301 meshes with a sun gear 306 connect to an input shaft 305, and the second pinion gear 302 meshed with a ring gear 308 fixed to a case 307.
In addition, Patent Document 1 discloses a drive device for a vehicle in which the double pinion type planetary speed reduction mechanism and bevel gear type differential mechanism are combined with each other.
As a differential mechanism between right and left wheels of a vehicle, a double pinion double sun type planetary differential mechanism is known in the related art (for example, refer to Patent Document 2). As illustrated in FIG. 13, the double pinion double sun type planetary differential mechanism is configured so that a left axle 401 and a right axle 402 are coaxially arranged a left wheel pinion gear 404 and a right wheel pinion gear 405 are rotatably attached to a carrier 403 connected to an input shaft, the left wheel pinion gear 404 and the right wheel pinion gear 405 mesh with each other, a left wheel sun gear 406 connected to the left axle 401 meshes with the left wheel pinion gear 404, and a right wheel sun gear 407 connected to the right axle 402 meshes with the right wheel pinion gear 405.